What is the efficacy of medications used in the treatment of Pasteurella multocida infection?

Updated: Nov 07, 2019
  • Author: Sara L Cross, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

Antimicrobial resistance among Pasteurella isolates is rarely reported in humans. Tetracyclines, erythromycin, and penicillin are most commonly associated with resistance. Penicillin-resistant strains have been isolated only from respiratory tract infections. Most animal-bite injuries can be treated with oral antimicrobials on an outpatient basis. Severe or partially responding infections may necessitate hospitalization and parenteral antimicrobial administration, along with surgical intervention.

Most Pasteurella isolates are susceptible to oral antimicrobials such as amoxicillin, amoxicillin/clavulanic acid, minocycline, fluoroquinolones (ciprofloxacin, ofloxacin, levofloxacin, moxifloxacin), and trimethoprim-sulfamethoxazole. Based on in vitro susceptibility data, several antimicrobials should not be used empirically for P multocida infections, including dicloxacillin, vancomycin, cephalexin, cefaclor, cefadroxil, erythromycin, and clindamycin. Macrolide resistance is usually encountered with erythromycin. Other macrolides, including azithromycin, clarithromycin, and telithromycin (in order of decreasing susceptibility), retain in vitro activity against most Pasteurella strains. Aminoglycosides have poor activity against P multocida.

More-severe infections may require parenteral antibiotics. Intravenous ampicillin-sulbactam, ticarcillin-clavulanate, piperacillin-tazobactam, cefoxitin, and carbapenems (imipenem-cilastatin, meropenem, ertapenem) are excellent empiric options for animal-bite injuries, providing gram-positive, gram-negative, and anaerobic coverage. The tetracycline-derivative tigecycline also has excellent in vitro activity against P multocida and other pathogens encountered in animal and bite injuries. If P multocida is the only isolated organism, therapy may be changed to intravenous penicillin G. Once clinical improvement is noted, oral penicillin VK is an option. Patients with penicillin allergies can receive minocycline, doxycycline, fluoroquinolones, trimethoprim-sulfamethoxazole, or azithromycin.

The duration of therapy for P multocida infections has not been well established and can be tailored to clinical response. Milder soft-tissue infections usually require 7-10 days of oral therapy. More-severe cases can be treated for 10-14 days. Deep-tissue infections often require 4-6 weeks of treatment, usually with intravenous therapy initially.


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